Femtosecond detection found that the crosslinking chemical reaction of amine cured epoxy resin is very complicated, and many competitive reactions have been confirmed. The reaction between aliphatic primary amine and epoxy group can be carried out at room temperature without accelerant, but substances such as carboxylic acid, alcohol, phenol, sulfonic acid and water can accelerate the reaction, while substances such as ether, ketone, ester and nitrile can inhibit the reaction.

The order of promoting effect is acid > phenol > water > alcohol > aromatic hydrocarbon (toluene, etc.). ) > dioxane > diisopropyl ether. It should be pointed out that phthalic acid and maleic acid have no promoting effect.

The activity of aromatic amines is not as good as that of aliphatic amines, and the reaction rate with epoxy groups is slow, with only about 30% participating in the reaction at room temperature. The reason is that the electrons on N atom are dispersed by benzene ring, which weakens the basicity and steric effects of benzene ring. However, the reaction rate of aromatic amines with alicyclic epoxy groups is faster than that of aliphatic amines, which may be related to the high acidity of aromatic amines. Can be expressed by the following general formula: